The present invention relates generally to edge card connectors, and more particularly to connectors that utilize flexible circuitry as the connector contacts and which have an improved card engagement means.
Connectors are well known in the art which provide a connection between a primary circuit board and a secondary circuit board and are commonly referred to in the art as edge card connectors. These connectors typically include an insulative housing having a slot extending lengthwise within the housing that receives an edge of the secondary circuit card and a plurality of contacts on opposing sides of the slot. These contacts are typically stamped and formed and thus such connectors are limited in their "pitch", i.e., the spacing between the contacts. Where the connector contacts are stamped and formed, the stamping and forming process limits the pitch that can be obtained to about 0.5 mm.
By using flexible circuitry for the contacts, smaller pitches of about 0.3 mm may be obtained. Flexible circuitry has been incorporated in some edge card connectors, such as those shown in U.S. Pat. No. 3,614,707 issued Oct. 19, 1971 and U.S. Pat. No. 5,427,533 issued Jan. 27, 1995. These two connectors have flexible circuitry extending over their connector slots so that a circuit card may be inserted into and withdrawn from the connector slot as needed.
Applicant's copending patent application, Ser. No. 08/635,049 now U.S. Pat. No. 5,679,018, filed Apr. 17, 1996 for "Circuit Card Connector Utilizing Flexible Film Circuitry" describes a card connector utilizing flexible circuitry and having a reliable circuit card-engaging means that applies and maintains a reliable contact force on the conductive traces that are formed on the circuit card. Although reliable, it has been discovered that this connector construction has some disadvantages. The base member of the housing is typically die-cast and includes feet that extend laterally outwardly from the connector. The flexible circuitry conductive portions that are soldered to conductive traces on the circuit board extend around and under these feet. The conductive portions of the flexible circuitry are typically soldered to the traces on the circuit board, while the connector feet press the flexible circuitry conductive portions against the circuit board traces.
In these type of connectors, it has been found that forces generated by the insertion and withdrawal of the circuit card from the connector may be transmitted from the base member through the feet directly to the soldered connections between the flexible circuitry and the conductive traces on the circuit board. Failure of some of the soldered connections may result from this force transfer. It may also be difficult to control the coplanarity of the conductive portions of the flexible circuitry because of the die-cast process. The occasional variability of printed circuit boards to which the connector is mounted also may create coplanarity problems. Still further, the die-cast metal composition of the base member feet may unintentionally transfer substantial amount of heat away from the flexible circuitry conductive portions during soldering which may result in bad solder joints and affect the electrical integrity of the signals passing therethrough.
Accordingly, a need for a flexible circuitry connector having an isolation member as part of its base exists.
Such a connector is not present or suggested by the prior art. U.S. Pat. No. 5,564,931, issued Oct. 15, 1996 describes an edge card connector using flexible circuitry that has a solid base member that has a plurality of feet integrally formed therewith. U.S. Pat. No. 5,308,249, issued May 3, 1994 describes an edge card connector using flexible circuitry that relies upon a pair of L-shaped members that serve as the feet and contacts of the connector. Neither of these prior art connectors offers a solution to the aforementioned disadvantages.